One of the best places at LHR to get a good view indoors. Coffee and food are good too. Make sure you get the comfy armchairs by the window! When they use the runway for departures it's great.
Quite relaxed, coffee fine though lacks foam art. Queuing system could be a little more clear. Good view of the runway if that sort of thing gets you excited.
Seems a little cheeky for Caffe Nero at terminal 5 to be charging extra if you eat/drink in. Particularly given that the "in" is adjacent and identical to the "out".